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SubjectRe: [rtc-linux] [PATCH V2 3/5] gpio: add support for AMS AS3722 gpio driver
On Monday 23 September 2013 02:56 PM, Linus Walleij wrote:
> On Mon, Sep 23, 2013 at 10:55 AM, Laxman Dewangan <ldewangan@nvidia.com> wrote:
>> On Monday 23 September 2013 01:36 PM, Linus Walleij wrote:
>>> This is pin control. Do not try to shoehorn pin control drivers into
>>> the GPIO subsystem. Take a good day off, read through
>>> Documentation/pinctrl.txt and come back with a thoroughly rewritten
>>> driver in drivers/pinctrl/pinctrl-as3722.c.
> (...)
>> Yes, the appropriate location is pin control for pull up/down etc
>> configuration but with this device, the actual issue is with the way it is
>> require to configure the pull up/down and input/output of the pin. There is
>> no separate bits for pull up/down and direction and it is clubbed together.
>> The register's bits are defined as:
>>
>> Selects the GPIO mode (I, I/O, Tri, Pulls) (BIT 2:0)
>> 0 : Input
>> 1 : Output (push and pull) VSUP_GPIO
>> 2 : Output/Input (open drain, only NMOS is active)
>> 3 : ADC input (Tristate)
>> 4 : Input with pull-up to VDD_GPIO_lv
>> 5 : Input with pull-down
>> 6 : Output/Input open drain (nmos) with pull-up to VDD_GPIO_lv,
>> 7 : Output (push and pull) VDD_GPIO_lv
>>
>> So I can not actually configure the pull up/down, open drain and direction
>> independently until every thing is known.
>> Direction come from gpio driver but pull up/down and open drain
>> configuration come from the pin control.
>> And this is only the reason to make all configuration in single driver.
> This is nothing special. Create a single combined GPIO and
> pin control driver using the pin control framework and device
> tree bindings.
>

Ok, I was thinking that we should not call gpiochip_add() from the pin
control driver in any new driver and that's why I developed gpio driver
but it seems it is allowed. I saw some of driver in pinctrl are doing
pin control and gpio functionality in single driver i.e.
pincntrl-nomadik, pinctrl-samsung, pincntrl-st etc.
So this gpio driver can be moved now to the pincntrl folder and can use
pincontrol and gpio framework.

I will respin the change.




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